SSINS NO.: 6835
IN 83-74
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D. C. 20555
November 3, 1983
Information Notice No. 83-74: RUPTURE OF CESIUM-137 SOURCE USED IN
WELL-LOGGING OPERATIONS
Addressees:
All NRC licensees authorized to possess and use sealed sources containing
byproduct or special nuclear material in well-logging operations.
Purpose:
The intent of this information notice is to alert licensees to a potentially
serious problem identified as a result of an effort to remove a sealed
source from its holder. The source removal effort resulted in the rupture of
a cesium-137 sealed source and subsequent personnel and area contamination.
Description of Circumstances:
On the afternoon of September 14, 1983, Shelwell Services, Inc., authorized
to use well-logging sources for well-logging operations reported to NRC
Region III that, while attempting to remove a cesium-137 sealed source from
its source holder, the source was inadvertently ruptured. The source holder
is believed to be a stainless steel tube approximately 2.5 inches long and
1-5/8 inches in diameter, housing a nominal 2-curie cesium-137 sealed source
capsule, containing powdered cesium chloride. The source holder was to be
used in a density well-logging tool. At approximately 4:00 p.m. on September
13, the licensee was attempting to remove the cesium source from its holder
and place it in a different holder to accommodate the density tool.
Two licensee employees initially attempted to dislodge the source capsule by
inserting a lubricant into the source holder and tapping the holder. The
licensee had successfully removed other sources from source holders on
previous occasions using this same method. After repeated unsuccessful
attempts, three employees placed the source holder on a turning lathe and
using a drill bit, attempted to push the source out of its holder. With the
source holder concentrically spinning about the drill bit's axis, the source
capsule was ruptured. When the holder was removed from the lathe, the source
fell into a rag. The individuals noticed a hole in the source capsule. The
licensee initially reported to the NRC contamination of about a
ten-square-foot area within its facility with no resultant personnel or
offsite contamination. However, because of inadequate surveys, the licensee
failed to evaluate the
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situation and take immediate corrective actions, to limit personnel exposure
and spread of contamination. Radiation surveys were initially performed by
the licensee and showed the instrument to go beyond,its highest range.
Another radiation survey was performed using a different instrument and it
also went off-scale. The licensee interpreted these observations to be
instrument malfunctions and disregarded the off-scale readings. All
individuals working in the area, (a total of eleven including the three
working with the source) left the site at their usual quitting time unaware
of the seriousness of the incident. This resulted in significant spread of
contamination to numerous private homes and vehicles, in addition to
personnel contamination. Lower levels of radioactivity were found at three
business establishments.
To date, NRC, DOE, and State of Ohio representatives have identified
contamination at a total of fourteen private residences and three public
places. Most of the contaminated areas identified were 0.2-mrem/hr,
direct-surface-gamma, but several isolated spots in private residences
showed radiation levels up to 2-10 mrems/hr and one as high as 100 mrems/hr.
The three individuals involved in the source removal received some internal
deposition of radioactive material, none of which exceeded regulatory
limits. These individuals are undergoing examination under the direction of
an NRC medical consultant. Film badges for these three individuals showed
whole-body exposures of 13.48, 2.71, and 0.110 rems for the period August
25, 1983 through September 15, 1983. A consultant firm, hired by the
licensee, has completed decontamination of residences, public
establishments, and vehicles. A decontamination plan is to be submitted for
approval to decontaminate the licensee's facility. Decontamination costs are
estimated to be approximately $250,000.
Initial surveys of onsite facilities showed significant contamination levels
in three buildings. These levels ranged from 1.0 mrem/hr up to 600 mrems/hr.
As a consequence of the accident, the licensee has been ordered to cease all
operations, except those related to decontamination efforts, and to show
cause why the license should not be revoked.
Another well-logging incident recently occurred resulting in a significant
spread of contamination. See Information Notice No. 83-32, dated May 26,
1983, titled, "Rupture of Americum-241 Source(s) Contained in a Well-Logging
Device." In that incident, the licensee also failed to recognize immediately
the spread of contamination resulting in extensive cleanup.
Discussion:
We suggest recipients review their procedures for well-logging source
changes to ensure that source capsules cannot be ruptured or source
containment breached during any operation. Written procedures should be
established for installation and removal of sources from source holders
and/or well-logging tools. Direct handling of bare sources should always be
avoided. We also
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IN 83-74
November 3, 1983
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suggest recipients review their procedures and training programs to ensure
that appropriate and operable radiation monitoring equipment is available
and used to alert personnel to possible source damage or high radiation
levels, so that appropriate protective and remedial actions can be
implemented. Emergency procedures should be developed to notify the
radiation safety officer or other responsible individual if there appears to
be a breach in a radioactive source and a possibility of contamination
spread.
In view of the potentially high cost of decontamination operations following
an incident, you should review your insurance coverage and determine if it
is adequate to pay for decontamination costs in the event of an incident.
If you have any questions regarding this matter, please contact the
Administrator of the appropriate NRC Regional Office or this office.
James G. Partlow, Acting Director
Division of Quality Assurance, Safeguards,
and Inspection Programs
Office of Inspection and Enforcement
Technical Contact: J. R. Metzger, IE
(301) 492-4947
Attachment:
Recently Issued IE Information Notices
.